In medical and technical endoscopy, as a rule it is necessary to illuminate the object under observation. To generate illuminating light with a high light beam and desired spectral properties, in particular good color reproduction, use is often made of separate light source devices with high-pressure gas discharge lamps, halogen bulbs or other light sources. The light source device is connected with the proximal end of the endoscope by means of a flexible light-conducting cable. The illuminating light is transmitted from the proximal end to the distal end of the endoscope by means of one or more bundles of light-conducting fibers.
Considerable effort is required in constructing and manufacturing endoscopes for precise arrangement of the light-conducting fibers, in particular their proximal and distal ends. A further difficulty in construction and manufacture is the fact that, between the light-conducting cable and the light outlet surfaces on the distal end of the endoscope, the divergence or angular distribution of the illuminating light needs to be adjusted to the visual field (in the sense of a solid angle) that is to be illuminated. Often used here is a so-called fiber cone, which is produced as a separate component and mounted on the proximal end of the endoscope. A fiber cone includes a short bundle of light-conducting fibers whose cross-sections change from the light inlet surface to the light outlet surface, in particular becoming smaller. The light outlet surface of the fiber cone and the light inlet surface of the bundle of light-conducting fibers must be combined with one another in such a way that a low-loss optical coupling is durably ensured.
There is a clear tendency to produce constantly thinner endoscope shafts. Conventional concepts are reaching their limits in terms of increasing miniaturization, but have proved themselves in wide applications over time and have been considerably optimized. It is therefore especially difficult to predict, in the case of endoscopes, which aspects of conventional concepts can be further developed and exploited and which aspects lend themselves to fundamental new departures. The present invention focuses on selected aspects of the illuminating beam path.